I am not sure whats different but I just upgraded today to KDE 4.8.4 and I have to say it does not seam much different but the performance is great.
I didn't have a performance problem before but this build really likes this system. Its incredibly snappy and a pleasure to use. It just seams like everything just works better. Its hard to explain but I just wanted to come by and tell you guys great job and thank you for the great desktop.

System specs
AMD FX-4100 Quadcore overclocked to 4000Mhz
8Gb DDR3
ASUS M5A-97
Nvidia 7900GS (Dual monitors)
Kingston SSD (root)
WD 500Gb (Home)